An elasto-plastic constitutive model of moderate sandy clay based on BC-RBFNN

Application research of neural networks to geotechnical engineering has become a hotspot nowadays.General model may not reach the predicting precision in practical application due to different characteristics in different fields.In allusion to this,an elasto-plastic constitutive model based on clustering radial basis function neural network(BC-RBFNN) was proposed for moderate sandy clay according to its properties.Firstly,knowledge base was established on triaxial compression testing data;then the model was trained,learned and emulated using knowledge base;finally,predicting results of the BC-RBFNN model were compared and analyzed with those of other intelligent model.The results show that the BC-RBFNN model can alter the training and learning velocity and improve the predicting precision,which provides possibility for engineering practice on demanding high precision.     

Creep testing and viscous behavior research on carbon constructional quality steel under high temperature

Creep tests under at a certain temperature and different stress levels were performed on two carbon constructional quality steels at a certain stress level and different temperatures,and their creep curves at high temperature were obtained based on analyzing the testing data.Taking 45 steel at a certain temperature and stress as the example,the integral creep constitutive equation and the differential stress-strain constitutive relationship were established based on the relevant rheological model,and the integral core function was also obtained.Simultaneously,the viscous coefficients denoting the viscous behavior in visco-plastic constitutive equation were determined by taking use of the creep testing data.Then the viscous coefficients of three carbon steels(20 steel,35 steel and 45 steel) were compared and analyzed.The results show that the viscosity is different due to different materials at the same temperature and stress.     

再生混凝土的抗冻性能研究

旨在研究未掺任何外加剂的再生混凝土的抗冻性能。即再生混凝土在硬化初期受到一次冻结对其质量的影响,用抗压强度来表征它的力学性能。同时研究经过在标准条件下养护几天后再受冻的再生混凝土的早期抗冻能力,并分析影响再生混凝土抗冻性能的原因。     

Numerical simulation and its application ofrheological forming of titanium alloy vane disk

The hot rheological forming method was proposed to form the second titanium alloy vane disk. The hot rheological forming process of the TC 11 titanium vane disk under a certain temperature and different strain rates was investigated by using the bulk forming software of DEFORM 3D. A series of results including temperature field, equivalent strain distribution, load-stroke curve and rheology procedure were obtained by this finite element method. The rheological forming characteristics were well realized and the forming parameters were determined. The results and analysis show that with decreasing strain rate, the metal flow more equably and the filling of the vane shape is also better. Moreover, the mechanical properties and microstructures of the products produced by this new technique are improved evidently compared with that produced by traditional method.